Regional contrast enhancement based on complementary information to reflectivity information

ABSTRACT

Systems and methods for performing ultrasound imaging. Ultrasound information of a subject region in response to ultrasound pulses transmitted toward the subject region can be gathered. The ultrasound information can include reflectivity information and complementary information to the reflectivity information of the subject region in response to the ultrasound pulses. One or more ultrasound images of at least a portion of the subject region can be formed from the reflectivity information. Further, the one or more ultrasound images can be modified based on the complementary information to the reflectivity information to generate one or more enhanced ultrasound images from the one or more ultrasound images.

If an Application Data Sheet (ADS) has been filed on the filing date ofthis application, it is incorporated by reference herein. Anyapplications claimed on the ADS for priority under 35 U.S.C. §§ 119,120, 121, or 365(c), and any and all parent, grandparent,great-grandparent, etc. applications of such applications, are alsoincorporated by reference, including any priority claims made in thoseapplications and any material incorporated by reference, to the extentsuch subject matter is not inconsistent herewith.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit of the earliest availableeffective filing date(s) from the following listed application(s) (the“Priority Applications”), if any, listed below (e.g., claims earliestavailable priority dates for other than provisional patent applicationsor claims benefits under 35 USC § 119(e) for provisional patentapplications, for any and all parent, grandparent, great-grandparent,etc. applications of the Priority Application(s)).

Priority Applications:

This application is a continuation of U.S. patent application Ser. No.16/792,762, filed Feb. 17, 2020, for REGIONAL CONTRAST ENHANCEMENT BASEDON COMPLEMENTARY INFORMATION TO REFLECTIVITY INFORMATION, which claimspriority to U.S. Provisional Patent Application No. 62/827,984 to GlenW. McLaughlin et al., titled SOUND SPEED ESTIMATION FOR THE USE OFREGIONAL CONTRAST ENHANCEMENT OF GRAY SCALE IMAGES, and filed Apr. 2,2019, the entire disclosures of which are hereby incorporated herein bythis reference.

TECHNICAL FIELD

The present disclosure relates to ultrasound imaging and moreparticularly to modifying ultrasound images based on complementaryinformation to reflectivity information.

BACKGROUND OF THE INVENTION

Ultrasound imaging is widely used for examining a wide range ofmaterials and objects across a wide array of different applications.Ultrasound imaging provides a fast and easy tool for analyzing materialsand objects in a non-invasive manner. As a result, ultrasound imaging isespecially common in the practice of medicine as an ailment diagnosis,treatment, and prevention tool. Specifically, because of its relativelynon-invasive nature, low cost and fast response time ultrasound imagingis widely used throughout the medical industry to diagnose and preventailments. Further, as ultrasound imaging is based on non-ionizingradiation it does not carry the same risks as other diagnosis imagingtools, such as X-ray imaging or other types of imaging systems that useionizing radiation.

Ultrasound images typically suffer from limited contrast resolution as anumber of clinically significant structures have similar echogenicity tothat of background tissue. This limitation has resulted in physiciansusing other imaging modalities to more easily visualize the contrastresolution between healthy and disease tissue. Several techniques havebeen developed in order to improve the overall contrast resolution ofultrasound images, e.g. for purposes of improving contrast resolutionfor background tissue having similar echogenicity. Specifically,techniques for compounding images of either different frequencies,different orientations, or different nonlinear tissue properties havebeen developed, e.g. harmonic imaging has been developed. While suchtechniques do provide improvements in contrast resolution in ultrasoundimages, the amount of contrast resolution capable of being achievedthrough these techniques is still deficient.

SUMMARY

According to various embodiments, a method for performing ultrasoundimaging includes collecting ultrasound information of a subject regionin response to ultrasound pulses transmitted toward the subject region.The ultrasound information can include both reflectivity information andcomplementary information to the reflectivity information of the subjectregion in response to the ultrasound pulses. The method can also includeforming one or more ultrasound images of at least a portion of thesubject region from the reflectivity information. Further, the methodcan include modifying the one or more ultrasound images based on thecomplementary information to the reflectivity information to generateone or more enhanced ultrasound images from the one or more ultrasoundimages.

In certain embodiments, a system for performing ultrasound imagingincludes an ultrasound transducer and a main processing console. Theultrasound transducer can collect ultrasound information of a subjectregion in response to ultrasound pulses transmitted toward the subjectregion. The ultrasound information can include both reflectivityinformation and complementary information to the reflectivityinformation of the subject region in response to the ultrasound pulses.The main processing console can form one or more ultrasound images of atleast a portion of the subject region from the reflectivity information.The main processing console can also modify the one or more ultrasoundimages based on the complementary information to the reflectivityinformation to generate one or more enhanced ultrasound images from theone or more ultrasound images.

In various embodiments, a system for performing ultrasound imagingincludes one or more processors and a computer-readable medium providinginstructions accessible to the one or more processors to cause the oneor more processors to collect ultrasound information of a subject regionin response to ultrasound pulses transmitted toward the subject region.The ultrasound information can include both reflectivity information andcomplementary information to the reflectivity information of the subjectregion in response to the ultrasound pulses. The instructions canfurther cause the one or more processors to form one or more ultrasoundimages of at least a portion of the subject region from the reflectivityinformation. Additionally, the instructions can cause the one or moreprocessors to modify the one or more ultrasound images based on thecomplementary information to the reflectivity information to generateone or more enhanced ultrasound images from the one or more ultrasoundimages.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example of an ultrasound system.

FIG. 2 is a flowchart of an example method for modifying an ultrasoundimage based on complementary information to reflectivity information ofultrasound pulses used in generating the ultrasound image.

FIG. 3 is a flowchart of an example method for generating an ultrasoundimage with enhanced contrast resolution through the use of a sound speedmap.

FIG. 4 is an unenhanced B-Mode image with 5 known targets that differ inpropagation speed from a mean propagation speed.

FIG. 5 is a sound speed map of the actual propagation speeds of theultrasound pulses for the material and the five regions in the B-Modeimage shown in FIG. 4 .

FIG. 6 is a sound speed map of the estimated propagation speeddeviations from the mean of the phantom for the material and the fiveregions for the propagation speeds indicated by the sound speed mapshown in FIG. 5 .

FIG. 7 is a composite image including the B-Mode phantom and the soundspeed map overlaid with the mean propagation speed value removed.

FIG. 8 is an enhanced B-Mode image with contrast resolution that ismodified based on the sound speed map to adjust the gain of the areas ofdiffering propagation speeds.

DETAILED DESCRIPTION

Enhancing ultrasound images continues to be an important area of focus.Specifically, it is critical that ultrasound images can be enhanced toaccurately display information related to different types of tissue,e.g. in the same ultrasound image. In turn, this can allow doctors tomore easily diagnose diseases and provide treatments for the diseasesbased on their diagnoses.

In particular, as clinically significant structures often times havesimilar echogenicity to that of background tissue, it becomes verydifficult to create ultrasound images that represent distinguishingcharacteristics between the structures and the background tissue. Forexample, ultrasound images typically suffer from limited contrastresolution as a number of clinically significant structures have similarechogenicity to that of background tissue. In turn, it becomes difficultfor doctors to quickly and accurately diagnose diseases based on theseimages and provide treatments for such diseases.

Many attempts have been made to characterize underlying tissueproperties with ultrasound. One technology, in particular, has been usedto measure the speed of sound propagation within the tissue. However,obtaining a high-resolution sound speed map that can be used to correctfor wave dispersion of an ultrasound transmit can be difficult tocalculate. This makes it more difficult to characterize underlyingtissue properties through ultrasound and ultimately provide the abilityfor doctors to quickly and accurately provide medical diagnoses andtreatment.

The following disclosure describes systems, methods, andcomputer-readable media for solving these problems/discrepancies.Specifically, the present technology involves system, methods, andcomputer-readable media for collecting complementary information toreflectivity information generated through ultrasound pulses andenhancing or otherwise modifying ultrasound images based on thecomplementary information. More specifically, the present technologyinvolves systems, methods, and computer-readable media for identifyingone or more regions to modify in an ultrasound image based oncomplementary information to reflectivity information used to generatethe image. In turn, the one or more regions can be modified based on thecomplementary information, e.g. to enhance the quality of the ultrasoundimage or the contrast in the ultrasound image.

Specifically and as will be discussed in greater detail later, alow-resolution sound speed map can be generated based on collectedcomplementary information to reflectivity information. In turn, thesound speed map can be applied to enhance the contrast resolution of aB-Mode ultrasound image. The data used to produce the sound speed mapand the B-Mode image can be identical and generated through the sametransmit/receive profile(s). Alternatively, the data used to produce thesound speed map and the B-mode image can be distinctly gathered throughseparate transmit/receive profiles, e.g. to optimize the performance ofeach of the modalities.

Reference is now made to the figures, where like components aredesignated by like reference numerals throughout the disclosure. Some ofthe infrastructure that can be used with embodiments disclosed herein isalready available, such as general-purpose computers, computerprogramming tools and techniques, digital storage media, andcommunications networks. A computing device may include a processor suchas a microprocessor, microcontroller, logic circuitry, or the like. Theprocessor may include a special purpose processing device such as anapplication-specific integrated circuit (ASIC), programmable array logic(PAL), programmable logic array (PLA), programmable logic device (PLD),field programmable gate array (FPGA), or other customized orprogrammable device. The computing device may also include acomputer-readable storage device such as non-volatile memory, staticRAM, dynamic RAM, ROM, CD-ROM, disk, tape, magnetic, optical, flashmemory, or other non-transitory computer-readable storage medium.

Various aspects of certain embodiments may be implemented usinghardware, software, firmware, or a combination thereof. As used herein,a software module or component may include any type of computerinstruction or computer executable code located within or on acomputer-readable storage medium. A software module may, for instance,comprise one or more physical or logical blocks of computerinstructions, which may be organized as a routine, program, object,component, data structure, etc., which performs one or more tasks orimplements particular abstract data types.

In certain embodiments, a particular software module may comprisedisparate instructions stored in different locations of acomputer-readable storage medium, which together implement the describedfunctionality of the module. Indeed, a module may comprise a singleinstruction or many instructions, and may be distributed over severaldifferent code segments, among different programs, and across severalcomputer-readable storage media. Some embodiments may be practiced in adistributed computing environment where tasks are performed by a remoteprocessing device linked through a communications network.

The embodiments of the disclosure will be best understood by referenceto the drawings. The components of the disclosed embodiments, asgenerally described and illustrated in the figures herein, could bearranged and designed in a wide variety of different configurations.Furthermore, the features, structures, and operations associated withone embodiment may be applicable to or combined with the features,structures, or operations described in conjunction with anotherembodiment. In other instances, well-known structures, materials, oroperations are not shown or described in detail to avoid obscuringaspects of this disclosure.

Thus, the following detailed description of the embodiments of thesystems and methods of the disclosure is not intended to limit the scopeof the disclosure, as claimed, but is merely representative of possibleembodiments. In addition, the steps of a method do not necessarily needto be executed in any specific order, or even sequentially, nor need thesteps be executed only once.

FIG. 1 is a schematic block diagram of one exemplary embodiment of amedical imaging device, such as an ultrasound imaging device 100. Thoseskilled in the art will recognize that the principles disclosed hereinmay be applied to a variety of medical imaging devices, including,without limitation, an X-ray imaging device, a computed tomography (CT)imaging device, a magnetic resonance imaging (MRI) device, and apositron-emission tomography (PET) imaging device. As such, thecomponents of each device may vary from what is illustrated in FIG. 1 .

In one embodiment, the ultrasound imaging device 100 may include anarray focusing unit, referred to herein as a beam former 102, by whichimage formation can be performed on a scanline-by-scanline basis. Thedevice may be controlled by a master controller 104, implemented by amicroprocessor or the like, which accepts operator inputs through anoperator interface and in turn controls the various subsystems of thedevice 100.

For each scanline, a transmitter 106 generates a radio-frequency (RF)excitation voltage pulse waveform and applies it with appropriate timingacross a transmit aperture (defined, in one embodiment, by a sub-arrayof active elements) to generate a focused acoustic beam along thescanline.

RF echoes received by one or more receive apertures or receiver 108 areamplified, filtered, and then fed into the beam former 102, which mayperform dynamic receive focusing, i.e., realignment of the RF signalsthat originate from the same locations along various scan lines.Collectively, the transmitter 106 and receiver 108 may be components ofa transducer 110. Various types of transducers 110 are known in theultrasound imaging art, such as linear probes, curvilinear probes, andphased array probes.

An image processor 112 may perform processing tasks specific to variousactive imaging mode(s) including 2D scan conversion that transforms theimage data from an acoustic line grid into an X-Y pixel image fordisplay. For other modes, such as a spectral Doppler mode, the imageprocessor 112 may perform wall filtering followed by spectral analysisof Doppler-shifted signal samples using typically a sliding FFT-window.The image processor 112 may also generate a stereo audio signal outputcorresponding to forward and reverse flow signals. In cooperation withthe master controller 104, the image processor 112 may also formatimages from two or more active imaging modes, including displayannotation, graphics overlays and replay of cine loops and recordedtimeline data.

A cine memory 114 provides resident digital image storage to enablesingle image or multiple image loop review, and acts as a buffer fortransfer of images to digital archival devices, such as hard disk drivesor optical storage. In some systems, the video images at the end of thedata processing path may be stored to the cine memory. Instate-of-the-art systems, amplitude-detected, beamformed data may alsobe stored in cine memory 114. For spectral Doppler mode, wall-filtered,baseband Doppler 1/Q data for a user-selected range gate may be storedin cine memory 114. Subsequently, a display 116, such as a computermonitor, may display ultrasound images created by the image processor112 and/or images using data stored in the cine memory 114.

The beam former 102, the master controller 104, the image processor 112,the cine memory 114, and the display 116 can be included as part of amain processing console 118 of the ultrasound imaging device 100, whichmay include more or fewer components or subsystems than are illustrated.The ultrasound transducer 110 may be incorporated into an apparatus thatis separate from the main processing console 118, e.g. in a separateapparatus that is wired or wirelessly connected to the main processingconsole 118. This allows for easier manipulation of the ultrasoundtransducer 110 when performing specific ultrasound procedures on apatient. Further, the transducer 110 can be an array transducer thatincludes an array of transmitting and receiving elements fortransmitting and receiving ultrasound waves.

Those skilled in the art will recognize that a wide variety ofultrasound imaging devices are available on the market, and additionaldetails relating to how images are generated is unnecessary for athorough understanding of the principles disclosed herein. Specifically,the systems, methods, and computer-readable media described herein canbe applied through an applicable ultrasound imaging device of the widevariety of ultrasound imaging devices available on the market.

FIG. 2 is a flowchart 200 of an example method for modifying anultrasound image based on complementary information to reflectivityinformation of ultrasound pulses used in generating the ultrasoundimage. The example method shown in FIG. 2 , and other methods andtechniques for ultrasound imaging described herein, can be performed byan applicable ultrasound imaging system, such as the ultrasound system100 shown in FIG. 1 . For example, the techniques for ultrasound imagingdescribed herein can be implemented using either or both the ultrasoundtransducer 110 and the main processing console 118, e.g. the imageprocessor 112, of the ultrasound system 100.

At step 202, ultrasound information of a subject region is collected.The ultrasound information includes both reflectivity information andcomplementary information to the reflectivity information generated inresponse to ultrasound pulses transmitted towards the subject region.Specifically, reflectivity information generated based on theinteraction of ultrasound pulses with the subject region can becollected at step 202. Further, complementary information to thereflectivity information generated based on the interaction ofultrasound pulses with the subject region can be collected at step 202.The reflectivity information and the complementary information can begenerated by an applicable ultrasound component, such as ultrasoundtransducer 110 shown in FIG. 1 .

Reflectivity information includes applicable information used ingenerating ultrasound images of at least a portion of the subjectregion. Specifically, reflectivity information can include informationof reflections of ultrasound pulses transmitted into the subject region,e.g. information of backscattered ultrasound pulses. In turn and as willbe discussed in greater detail later, the information of the reflectionscan be used to generate ultrasound images through an applicableimaging/image formation technique.

Complementary information to the reflectivity information includesapplicable information that can be gathered from the ultrasound pulsestransmitted towards the subject region. Specifically, complementaryinformation to the reflectivity information can include applicableinformation that can be gathered form the ultrasound pulses that is notused in directly forming ultrasound images. Specifically, complementaryinformation to the reflectivity information can include propagationspeeds of the ultrasound pulses in interacting with the subject region,information related to elasticity of the subject region, informationrelated to stiffness of the subject region, and values of an acousticnonlinearity parameter associated with the subject region. For example,complementary information can include sound speeds of ultrasound pulsesas the pulses interact with the subject region and are reflected fromthe subject region. In another example, complementary information to thereflectivity information can include variations in lateral spatialspectral signals at varying depths.

The reflectivity information and the complementary information can begenerated through the same ultrasound pulses transmitted towards thesubject region. Specifically, the reflectivity information and thecomplementary information to the reflectivity information can begenerated through the same ultrasound transmit and receive profile(s).For example, a B-Mode image can be produced by compounding acrossframes, e.g. 2 to 9 frames, of image data. As follows the sameultrasound pulses used in creating the compounded frames of image datacan also be used to produce a number, e.g. 2 to 9, of sounds speed maps.In turn, the sound speed maps can be combined to generate an accurateestimate of sound speeds.

Further, the reflectivity information and the complementary informationcan be distinctly generated through different ultrasound pulsestransmitted towards the subject region. Specifically, the reflectivityinformation and the complementary information can be distinctlygenerated through separate ultrasound transmit and receive profiles. Forexample, a first ultrasound transmit and receive profile can be appliedto generate the reflectivity information and a second ultrasoundtransmit and receive profile can be applied to generate thecomplementary information separately from the reflectivity information.For example and with respect to propagation speed as the complementaryinformation, an ideal transmit profile for estimating propagation speedis not necessarily an optimized profile for B-Mode imaging, and viceversa. Accordingly, the complementary information for identifying thepropagation speed can be generated separately from the reflectivityinformation for performing B-mode imaging.

The reflectivity information and the complementary information can begenerated through the same ultrasound transmit receive profile(s) basedon characteristics of the subject region. Specifically, the reflectivityinformation and the complementary information can be created through theultrasound transmit receive profile(s) if the tissue being imaged isfast moving. For example, if the heart is the subject region, thenreflectivity information and the complementary information can begenerated through the same ultrasound pulses transmitted towards theheart as the heart is a fast-moving structure. Additionally, thereflectivity information and the complementary information can bedistinctly generated through different ultrasound transmit receiveprofiles based on characteristics of the subject region. Specifically,the reflectivity information and the complementary information can becreated through different ultrasound transmit receive profiles if thetissue being imaged is slow moving. For example, if the thyroid is thesubject region, then the reflectivity information and the complementaryinformation can be generated through different ultrasound pulsestransmitted towards the thyroid as the thyroid is a slow-movingstructure.

The complementary information can be generated over a plurality ofultrasound transmit and receive profiles to generate compoundcomplementary information. For example and as discussed previously, aplurality of sound speed maps can be generated across a plurality ofultrasound transmit and receive profiles to generate compoundcomplementary information including the plurality of sound speed maps.Further in the example, the plurality of sound speed maps can becompounded or otherwise combined to form a compound sound speed map ofthe compound complementary information. The compound complementaryinformation can be generated through a plurality of transmit and receiveprofiles that are separate from transmit and receive profile(s) used increating the reflectivity information. Further, the compoundcomplementary information can be generated through a plurality oftransmit and receive profiles that are also used to create thereflectivity information. The compound complementary information, aswill be discussed in greater detail later, can be applied to modify theone or more ultrasound images generated from the reflectivityinformation.

In forming the compound complementary information across a plurality ofultrasound transmit and receive profiles, artifacts can be filtered outfrom the complementary information used in generating the compoundcomplementary information. Specifically, the complementary informationcan be combined, when forming the compound complementary information, tofilter out artifacts from the complementary information. For example,when multiple sound speed maps are created through different transmitorigins, artifacts that are generated in each map will not be collocatedacross the sound speed maps with respect to the subject region. In turn,when the sound speed maps are combined the total number of artifacts ina combined sound speed map, e.g. the compound complementary information,can be reduced or otherwise eliminated. This can lead to improvements inenhancing or otherwise modifying ultrasound images with the compoundcomplementary information.

At step 204, one or more ultrasound images of at least a portion of thesubject region are formed from the reflectivity information. Ultrasoundimages formed at step 204 can be generated from the reflectivityinformation using an applicable technique. Specifically, B-Modeultrasound images can be formed from the reflectivity informationthrough one or more applicable B-Mode imaging techniques. Examples ofB-Mode imaging techniques include a fundamental imaging technique, afundamental spatial compounding imaging technique, a harmonic imagingtechnique, a harmonic spatial compounding imaging technique, afundamental and harmonic compounding imaging technique, and afundamental and harmonic spatial compounding imaging technique.

At step 206, the one or more ultrasound images are modified based on thecomplementary information to the reflectivity information to generateone or more enhanced ultrasound images. Specifically, the ultrasoundimages can be modified to present information related to the subjectregion in a more clear and accurate manner. For example, a contrast inthe images can be modified to more clearly show different regionscorresponding to different types of tissue in the images of the subjectregion.

In modifying the one or more ultrasound images based on thecomplementary information, one or more regions can be identified in theultrasound images based on the complementary information. In turn, theidentified regions in the ultrasound images can be modified or enhanced,e.g. in response to identifying the one or more regions, to ultimatelymodify the one or more ultrasound images. For example, regions in anultrasound image corresponding to heart tissue in the subject region canbe identified based on the complementary information. As follows, theregions in the ultrasound image corresponding to the heart tissue can bemodified or otherwise enhanced to highlight the heart tissue in theultrasound image.

The one or more ultrasound images can be modified based on a relation ofthe complementary information to a mean of the complementaryinformation. The mean of the complementary information can correspond toall or a portion of the entire subject region in the one or moreultrasound images. With respect to propagation speed, a propagationspeed mean across all or a portion of the subject region can beidentified from the propagation speeds included in the complementaryinformation. In turn, one or more regions in the ultrasound images canbe identified based on variations of the propagation speeds with respectto the propagation speed mean. Specifically, the one or more regions canbe identified based on variations of the propagation speedscorresponding to the one or more regions and the propagation speed mean.For example, if propagation speeds of ultrasound pulses corresponding toa region vary by a specific amount, e.g. a threshold amount, withrespect to a propagation speed mean for the subject region, then theregion can be identified in the ultrasound image. Further in theexample, the region can be separated from surrounding regions in theultrasound image if the propagation speeds of ultrasound pulsescorresponding to the surrounding regions fail to vary by the specificamount, e.g. the threshold amount, with respect to the propagation speedmean for the subject region.

Additionally, the one or more ultrasound images can be modified based ona relation of the complementary information to one or more absolutevalues of the complementary information. The absolute value of thecomplementary information can correspond to all or a portion of theentire subject region in the one or more ultrasound images. With respectto propagation speed, absolute value(s) of variations between apropagation speed mean across all or a portion of the subject region canbe identified from the propagation speeds included in the complementaryinformation. In turn, one or more regions in the ultrasound images canbe identified based on the absolute value(s) of variations between thepropagation speeds and the propagation speed mean. Specifically, the oneor more regions can be identified based on absolute value(s) ofvariations between the propagation speeds corresponding to the one ormore regions and the propagation speed mean. For example, if an absolutevalue of the variation between propagation speeds of ultrasound pulsesfor a region and a propagation speed mean is greater than a specificamount, e.g. threshold amount, then the region can be identified in theultrasound image. Further in the example, the region can be separatedfrom surrounding regions in the ultrasound image if absolute value(s) ofthe variation between propagation speeds of ultrasound pulses of thesurrounding regions and the propagation speed mean are less than thespecific amount, e.g. the threshold amount.

In modifying the one or more identified regions of the ultrasoundimage(s), the regions can be modified in an applicable way todistinguish the one or more identified regions from the surroundingareas in the ultrasound image(s). Specifically, the one or moreidentified regions can be colored to distinguish the region(s) from thesurrounding areas to the region(s) in the ultrasound image(s). Morespecifically, the region(s) can be colored in a specific manner based onthe complementary information corresponding to the region(s). Forexample, the region(s) that have corresponding sound propagation speedsthat are above a mean propagation speed can be colored as red. Furtherin the example, the region(s) that have corresponding sound propagationspeeds that are below the mean propagation speed can be colored as blue.In another example, the mean sound speed velocity of tissue can benormalized and regions that deviate from the mean can be colored toproduce a transparent color overlay that can be added to a B-Mode image.In turn, this can provide direct information to the clinician as towhere there are deviations of the tissue properties as estimated fromthe sound speed variations.

Further, brightness levels in the one or more identified regions can bemodified to distinguish the region(s) from the surrounding areas to theregion(s) in the ultrasound image(s). More specifically, the brightnesslevels in the region(s) can be adjusted based on the complementaryinformation corresponding to the region(s). For example, brightnesslevels in the region(s) that have corresponding sound propagation speedsthat are above a mean propagation speed can be increased. Further in theexample, brightness levels in the region(s) that have correspondingsound propagation speeds that are below the mean propagation speed canbe decreased.

Additionally, one or more gains for the one or more ultrasound imagescan be modified as part of modifying the one or more ultrasound images.Specifically, gain(s) of the identified region(s) in the ultrasoundimages can be modified, e.g. in response to identifying the region(s) inthe ultrasound images based on the complementary information. The gainscorresponding to the identified regions in the ultrasound images can bemodified based on the complementary information, e.g. the samecomplementary information used to identify the regions. Specifically,the gain of the identified regions in the ultrasound images can bemodified based on an amount of variation between complementaryinformation corresponding to the regions and an average of at least aportion of the complementary information.

Gains for the ultrasound images can be adjusted based on propagationspeeds of ultrasound pulses corresponding to the ultrasound images.Specifically, gains in the identified regions can be adjusted based onpropagation speeds of the ultrasound pulses corresponding to theidentified regions. More specifically, gains in the identified regionscan be adjusted based on variations between the propagation speeds ofthe ultrasound pulses corresponding to the identified regions and thepropagation speed mean. For example, gains in regions of the ultrasoundimage(s) with propagation speeds that are greater than the propagationspeed mean can be increased and gains in regions of the ultrasoundimage(s) with propagation speeds that are less than the propagationspeed mean can be decreased. Alternatively, gains in regions of theultrasound image(s) with propagation speeds that are less than thepropagation speed mean can be increased and gains in regions of theultrasound image(s) with propagation speeds that are greater than thepropagation speed mean can be decreased.

Further, gains for the ultrasound images can be adjusted based on anamount of variation between the complementary information and an averageof at least a portion of the complementary information with respect to athreshold. Specifically, gains for the ultrasound images can be adjustedbased on an amount of variation between propagation speeds and thepropagation speed mean with respect to a threshold. For example, if theamount of variation between propagation speeds of pulses for a regionand the mean propagation speed is greater than a threshold amount, thenone or more gains for the region can be increased. Further in theexample, if the amount of variation between propagation speeds of pulsesfor a region and the mean propagation speed is less than the thresholdamount, then one or more gains for the region can be decreased.Alternatively, if the amount of variation between propagation speeds ofpulses for a region and the mean propagation speed is greater than athreshold amount, then one or more gains for the region can bedecreased. In turn, if the amount of variation between propagationspeeds of pulses for a region and the mean propagation speed is lessthan the threshold amount, then one or more gains for the region can beincreased. A threshold for applying the techniques described here, e.g.a threshold for adjusting gain, can be defined according to anapplicable technique and/or by an applicable entity. For example, anoperation of an ultrasound system can define a threshold for selectivelyadjusting gain in one or more ultrasound images based on thecomplementary information.

The techniques of identifying the one or more regions in the ultrasoundimage(s) based on the complementary information and modifying theultrasound image(s) based on the complementary information can beachieved using one or more sound speed maps. A sound speed map caninclude a mapping of propagation speeds of ultrasound pulses across thesubject region. Further, a sound speed map can correspond to the one ormore ultrasound images. Specifically, a region in the sound speed mapcan correspond to a specific region in an ultrasound image such thatpropagation speeds of ultrasound pulses in the region of the sound speedmap are propagation speeds of ultrasound pulses corresponding to thespecific region in the ultrasound image. For example, propagation speedsin a region of the sound speed map can indicate propagation speeds ofultrasound pulses interacting with specific heart tissue. In turn, theportion of an ultrasound that includes the heart tissue can correspondto the region of the sound speed map that indicated the propagationspeeds of ultrasound pulses interacting with the heart tissue.

One or more sound speed maps can be generated from the complementaryinformation to the reflectivity information. As follows, the one or moreregions in the ultrasound image(s) can be identified using the soundspeed map(s). For example, a region can be identified from a sound speedmap if the propagation speeds for ultrasound pulses of the region, asindicated by the sound speed map, are above a mean propagation speed. Inturn, the one or more regions identified using the sound speed map(s)can be modified based on the sound speed map(s).

FIG. 3 is a flowchart 300 of an example method for generating anultrasound image with enhanced contrast resolution through the use of asound speed map. As described previously, the sound speed map can begenerated through distinct ultrasound pulses that are separate from theultrasound pulses used to generate an ultrasound image. Alternatively,the sound speed map can be generated through the same ultrasound pulsesthat are used to generate an ultrasound image. In the example methodshown in the flowchart 300, independent transmit/receive frames are usedto generate the sound speed map. Specifically, at step 310 a transmitsequence that is optimized for estimation for the sound speed isidentified. At step 320, ultrasound pulses are transmitted towards theobject field according to the transmit sequence identified at step 310.Then, at step 330, the backscatter received from the object field isused to generate a sound speed map. At step 340, the imaging Tx/Rxsequence for imaging through B-Mode type imaging is identified. At step350, ultrasound pulses are transmitted towards the object fieldaccording to the imaging Tx/Rx sequence identified at step 340. At step360, a B-Mode image is generated based on the backscatter from the Tx/Rxsequence. At step 370, the B-Mode image is adaptively processed usingthe sound speed map. Specifically, regions where the sound speed variesfrom the normal in the B-Mode Image can be enhanced based on the soundspeed map. At step 380, the processed image is displayed.

FIG. 4 is an unenhanced B-Mode image 400 with 5 known targets thatdiffer in propagation speed from a mean propagation speed. The knowtargets in the B-Mode image 400 are extremely difficult to see as theirbackscatter properties only differ slightly from the backscatterproperties of the surround regions, e.g. surrounding material. The firsttarget that has a higher sound speed than the mean is located at region402. The second target that has a lower sound speed than the mean islocated at region 404. The third target that has a slightly lower soundspeed than the mean is located at region 406. The four target that has ahigher sound speed than the mean is located at region 408, and the fifthtarget that has a lower sound speed than the mean is located at region410. As shown in the B-mode image 400, it is difficult to accuratelyvisualize where these regions 402-410 are located.

FIG. 5 is a sound speed map 500 of the actual propagation speeds of theultrasound pulses for the material and the five regions 402-410 in theB-Mode image 400 shown in FIG. 4 . The background sound speed of thephantom, surrounding region to the regions 402-410, is around 1.54mm/uS. The first region 402 is a small round region that has acorresponding ultrasound propagation speed of around 1.65 mm/uS. Thesecond region 404 is a small round region that has a correspondingultrasound propagation speed of around 1.45 mm/uS. The third region 406is a small round region that has a corresponding ultrasound propagationspeed of around 1.50 mm/uS. The fourth region 408 is a large roundregion that has a corresponding ultrasound propagation speed of around1.65 mm/uS. The fifth region 410 is a large round region that has acorresponding ultrasound propagation speed of around 1.43 mm/uS.

FIG. 6 is a sound speed map 600 of the estimated propagation speeddeviations from the mean of the phantom for the material and the fiveregions 402-410 for the propagation speeds indicated by the sound speedmap 500 shown in FIG. 5 . As can be seen the estimates of the soundspeed deviations are lower in resolution than the true targets in thephantom as the edges slowly vary back to the mean sound speed instead ofhaving an abrupt change. The first region 402, is estimated to differ byabout 0.05 mm/uS from the mean at the center and slowly transition backto the mean propagation speed. The second region 404 is estimated todiffer by about −0.06 mm/uS from the mean at the center and slowlytransition back to the mean propagation speed. The third region 406 isestimated to differ by about −0.02 mm/uS from the mean at the center andslowly transition back to the mean propagation speed. The fourth region408 is estimated to differ by about 0.06 mm/uS from the mean at thecenter and slowly transition back to the mean propagation speed. Thefifth region 410 is estimated to differ by about −0.10 mm/uS from themean at the center and slowly transition back to the mean propagationspeed.

The propagation speeds for the sound speed map 500 and the propagationspeed deviations shown in the sound speed map 600 can be gatheredthrough a low-resolution method, e.g. using ultrasound pulses operatingin a low-resolution imaging or information gathering mode. As shown inFIG. 6 , the low-resolution method of obtaining a robust estimateresults in the biasing of the propagation speed estimates towards themean for the smaller region, e.g. 402, 404, and 406. Even thoughobtaining a robust sound speed map estimate can result in alow-resolution image, this information can still be useful in indicatingwhere there are variations in propagation speed. In turn, theinformation indicating variation in propagation speed can be used toenhance the contrast resolution of the B-Mode image 400. Further, asmore robust higher resolution estimates of propagation speed are capableof being generated, this same adaptive combination of the sound speedmap and the B-Mode image only gets better.

FIG. 7 is a composite image 700 including the B-Mode phantom and thesound speed map 600 overlaid with the mean propagation speed valueremoved. As shown in FIG. 7 , the regions are more clearly visible thanin the B-Mode image 400 of FIG. 4 . The first region 402 shows a smallround target where the corresponding ultrasound propagation speed ishigher than the background. The second region 404 shows a small roundtarget where the corresponding ultrasound propagation speed is lowerthan the background. The third region 406 shows a small round targetwhere the corresponding ultrasound propagation speed is lower than thebackground. The fourth region 408 shows a large round target where thecorresponding ultrasound propagation speed is higher than thebackground. The fifth region 410 shows a large round target where thecorresponding ultrasound propagation speed is lower than the background.

FIG. 8 is an enhanced B-Mode image 800 with contrast resolution that ismodified based on the sound speed map 600 to adjust the gain of theareas of differing propagation speeds. Specifically, to create theenhanced B-Mode image 800, the un-altered gray scale level of thesubject region is measured from the background of the B-Mode image 400and enhanced by selectively adjusting the gain in portions of the B-Modeimage 400. The degree of gain enhancement that is applied isproportional to each region's 402-410 variation from the meanpropagation speed. As can be seen the overall contrast resolution of theregions of varying sound speed are clearly indicated as compared to theB-Mode image 400. The first region 402 has a higher correspondingultrasound propagation speed than the background and is decreased ingain to clearly show a small round structure. The second region 404 hasa lower corresponding ultrasound propagation speed than the backgroundand is increased in gain to clearly show a small round structure. Thethird region 406 has a lower corresponding ultrasound propagation speedthan the background and is increased in gain to clearly show a smallround structure. The fourth region 408 has a higher correspondingultrasound propagation speed than the background and is increased ingain to clearly show a large round structure. The fifth region 410 has alower corresponding ultrasound propagation speed than the background andis decreased in gain to clearly show a large round structure.

The techniques described herein can be applied in an applicableultrasound imaging mode, such as B-Mode, contrast-enhanced ultrasound(‘CEUS’), CD-Mode, 2D/3D/4D, and the like. Specifically, the techniquesdescribed herein are not limited to B-Mode but can also be applied toother modes where improved temporal resolution within a region ofinterest has substantial clinical benefits, such as CEUS.

This disclosure has been made with reference to various exemplaryembodiments including the best mode. However, those skilled in the artwill recognize that changes and modifications may be made to theexemplary embodiments without departing from the scope of the presentdisclosure. For example, various operational steps, as well ascomponents for carrying out operational steps, may be implemented inalternate ways depending upon the particular application or inconsideration of any number of cost functions associated with theoperation of the system, e.g., one or more of the steps may be deleted,modified, or combined with other steps.

While the principles of this disclosure have been shown in variousembodiments, many modifications of structure, arrangements, proportions,elements, materials, and components, which are particularly adapted fora specific environment and operating requirements, may be used withoutdeparting from the principles and scope of this disclosure. These andother changes or modifications are intended to be included within thescope of the present disclosure.

The foregoing specification has been described with reference to variousembodiments. However, one of ordinary skill in the art will appreciatethat various modifications and changes can be made without departingfrom the scope of the present disclosure. Accordingly, this disclosureis to be regarded in an illustrative rather than a restrictive sense,and all such modifications are intended to be included within the scopethereof. Likewise, benefits, other advantages, and solutions to problemshave been described above with regard to various embodiments. However,benefits, advantages, solutions to problems, and any element(s) that maycause any benefit, advantage, or solution to occur or become morepronounced are not to be construed as a critical, a required, or anessential feature or element. As used herein, the terms “comprises,”“comprising,” and any other variation thereof, are intended to cover anonexclusive inclusion, such that a process, a method, an article, or anapparatus that comprises a list of elements does not include only thoseelements but may include other elements not expressly listed or inherentto such process, method, system, article, or apparatus. Also, as usedherein, the terms “coupled,” “coupling,” and any other variation thereofare intended to cover a physical connection, an electrical connection, amagnetic connection, an optical connection, a communicative connection,a functional connection, and/or any other connection.

Those having skill in the art will appreciate that many changes may bemade to the details of the above-described embodiments without departingfrom the underlying principles of the invention. The scope of thepresent invention should, therefore, be determined only by the followingclaims.

What is claimed is:
 1. A method for performing ultrasound imagingcomprising: collecting ultrasound information of a subject region inresponse to ultrasound pulses transmitted toward the subject region, theultrasound information including reflectivity information and soundspeed information including propagation speeds of the ultrasound pulsesinteracting with the subject region; forming one or more B-modeultrasound images of at least a portion of the subject region from thereflectivity information; calculating, from the sound speed information,a mean propagation speed of the ultrasound pulses interacting with thesubject region; generating, from the sound speed information, a soundspeed map of the propagation speeds of the ultrasound pulses interactingwith at least a portion of the subject region; and automatically andselectively adjusting at least one of a gain, a contrast, or brightnesslevel of different portions of the one or more B-mode ultrasound imagesin relation to each portion's variation from at least one of the meanpropagation speed according to the sound speed map or one of moreabsolute values of propagation speed from the sound speed information toproduce one or more contrast-enhanced B-mode ultrasound images.
 2. Themethod of claim 1, wherein generating the sound speed map comprisesgenerating a plurality of sound speed maps for multiple frames ofultrasound information and compounding the plurality of sound speed mapsto produce the sound speed map.
 3. The method of claim 1, whereinforming the one or more B-mode ultrasound images comprises using one ormore B-mode imaging techniques including one or a combination of afundamental imaging technique, a fundamental spatial compounding imagingtechnique, a harmonic imaging technique, a harmonic spatial compoundingimaging technique, a fundamental and harmonic compounding imagingtechnique, and a fundamental and harmonic spatial compounding imagingtechnique.
 4. The method of claim 1, wherein the sound speed map has alower resolution than the one or more B-mode ultrasound images.
 5. Themethod of claim 1, wherein the reflectivity information and sound speedinformation are derived from the same ultrasound pulses in response tothe subject region including a first amount of motion, and wherein thereflectivity information and sound speed information are derived fromdifferent ultrasound pulses in response to the subject region includinga second amount of motion, wherein the first amount of motion is greaterthan the second amount of motion.
 6. The method of claim 1, furthercomprising identifying the different portions of the one or more B-modeultrasound images based on variations between the propagation speeds ofthe ultrasound pulses in the different portions with respect to one ormore thresholds.
 7. The method of claim 1, further comprising:identifying a corresponding absolute value of the variations between thepropagation speeds and the at least one of the mean propagation speed orthe one or more absolute values of propagation speed for each of thedifferent portions of the one or more B-mode ultrasound images; andmodifying the different portions of the one or more B-mode ultrasoundimages based on the corresponding absolute value of the variationsbetween the propagation speeds and the at least one of the meanpropagation speed or the one or more absolute values of propagationspeed for each of the different portions.
 8. The method of claim 1,wherein automatically and selectively adjusting further comprisescoloring the different portions the one or more B-mode ultrasoundimages.
 9. The method of claim 1, wherein automatically adjustingcomprises automatically increasing the at least one of the gain,contrast, or brightness level in the different portions where thepropagation speeds are higher according to the sound speed map than theat least one of the mean propagation speed or the one or more absolutevalues of propagation speed and automatically decreasing the at leastone of the gain, contrast, or brightness level in the different portionswhere propagation speeds according to the sound speed map are less thanthe at least one of the mean propagation speed or the one or moreabsolute values of propagation speed.
 10. The method of claim 1, whereinautomatically adjusting comprises automatically increasing the at leastone of the gain, contrast, or brightness level in the different portionswhere the propagation speeds according to the sound speed map are lowerthan the at least one of the mean propagation speed or the one or moreabsolute values of propagation speed and automatically decreasing thegain or brightness level in the different portions where propagationspeeds according to the sound speed map are higher than the at least oneof the mean propagation speed or the one or more absolute values ofpropagation speed.
 11. The method of claim 1, wherein automaticallyadjusting comprises decreasing the gain, contrast, or brightness levelin the different portions where variations between the propagationspeeds according to the sound speed map and the at least one of the meanpropagation speed or the one or more absolute values of propagationspeed are higher than a threshold and increasing the gain, contrast orbrightness level in the different portions where the variations betweenthe propagation speeds according to the sound speed map and the at leastone of the mean propagation speed or the one or more absolute values ofpropagation speed are lower than the threshold.
 12. The method of claim1, wherein automatically adjusting comprises increasing the gain,contrast or brightness level in the different portions where variationsbetween the propagation speeds and the at least one of the meanpropagation speed or the one or more absolute values of propagationspeed are higher than a threshold and decreasing the gain, contrast orbrightness level in the different portions where the variations betweenthe propagation speeds and the at least one of the mean propagationspeed or the one or more absolute values of propagation speed are lowerthan the threshold.
 13. A system for performing ultrasound imagingcomprising: an ultrasound transducer configured to collect ultrasoundinformation of a subject region in response to ultrasound pulsestransmitted toward the subject region, the ultrasound informationincluding reflectivity information and sound speed information includingpropagation speeds of the ultrasound pulses interacting with the subjectregion; and at least one processor configured to: form one or moreB-mode ultrasound images of at least a portion of the subject regionfrom the reflectivity information; calculate, from the sound speedinformation, a mean propagation speed of the ultrasound pulsesinteracting with the subject region; generate, from the sound speedinformation, a sound speed map of the propagation speeds of theultrasound pulses interacting with the subject region; and automaticallyand selectively a adjusting gain, contrast, or brightness level ofdifferent portions of the one or more B-mode ultrasound images inrelation to each portion's variation from the at least one of the meanpropagation speed according to the sound speed map or one or moreabsolute values of propagation speed from the sound speed information toproduce one or more contrast-enhanced B-mode ultrasound images.
 14. Thesystem of claim 13, wherein the at least one processor generates aplurality of sound speed maps for multiple frames of ultrasoundinformation and compounding the plurality of sound speed maps to producethe sound speed map.
 15. The system of claim 13, the at least oneprocessor is to form the one or more B-mode ultrasound images by usingone or more B-mode imaging techniques including one or a combination ofa fundamental imaging technique, a fundamental spatial compoundingimaging technique, a harmonic imaging technique, a harmonic spatialcompounding imaging technique, a fundamental and harmonic compoundingimaging technique, and a fundamental and harmonic spatial compoundingimaging technique.
 16. The system of claim 13, wherein the sound speedmap has a lower resolution than the one or more B-mode ultrasoundimages.
 17. The system of claim 13, wherein the reflectivity informationand sound speed information are derived from the same ultrasound pulsesin response to the subject region including a first amount of motion,and wherein the reflectivity information and sound speed information arederived from different ultrasound pulses in response to the subjectregion including a second amount of motion, wherein the first amount ofmotion is greater than the second amount of motion.
 18. The system ofclaim 13, further the at least one processor is further to identify thedifferent portions of the one or more B-mode ultrasound images based onvariations between the propagation speeds of the ultrasound pulses inthe different portions with respect to one or more thresholds.
 19. Thesystem of claim 13, wherein the at least one processor is further to:identify a corresponding absolute value of the variations between thepropagation speeds and the at least one of the mean propagation speed orthe one or more absolute values of propagation speed for each of thedifferent portions of the one or more B-mode ultrasound images; andmodify the different portions of the one or more B-mode ultrasoundimages based on the corresponding absolute value of the variationsbetween the propagation speeds and the at least one of the meanpropagation speed or the one or more absolute values of propagationspeed for each of the different portions.
 20. The system of claim 13,wherein the at least one processor is to automatically and selectivelyadjust at least one of a gain, a contrast, or brightness level ofdifferent portions of the one or more B-mode ultrasound images bycoloring the different portions the one or more B-mode ultrasoundimages.